Metabolised in mitochondria of cells during the citric acid cycle to produce ATP, creating CO2

Elimination

Exhalation as CO2, or combined with H2O to produce HCO3- and eliminated in urine

Resp

↓ Respiratory drive in all individuals. May result in a fatal ↓ in those dependent on hypoxic drive. Pulmonary toxicity due to free radial formation when PiO2>0.6bar - pneumonitis/ARDS due to lipid peroxidation of the alveolar-capillary membrane. Absorption atelectasis.

CVS

Improvement in all CVS parameters in the setting of hypoxia. However, hyperoxia ↓ CO, ↓PVR, ↓PAP, and causes coronary vasoconstriction with prolonged administration

CNS O2 toxicity, typically at pressures >1.6 bar though this is variable. Presents with a variety of neurological symptoms, progressing to disorientation and seizure. Retrolental fibroplasia in neonates exposed to high FiO2.